Preventative parasite treatments cover a wide range of nasties from worms to fleas. However, most contain fipronil or imidacloprid, which are banned in farming because of their seriously damaging effects on wildlife.

"One flea treatment of a medium-sized dog with imidacloprid contains enough pesticide to kill 60 million bees" Prof Dave Goulson, University of Sussex

I want my dog to be in good health but not at the cost of broken ecosystems, failed crops,famine, war, and the end of humanity ...

Are there alternative active ingredients that are less damaging but effective against the deathly parasites? e.g. fleas I could treat when found, but lungworm I'd like to prevent.


  • 2
    Welcome to Pets! Please take the tour to see how this site works, it only takes a minute. The quote sounds a lot like fear mongering to me personally... How many bees will come in touch with the flea treatment of your dog? Of course we consumers must dispose of the packaging and any leftovers in a responsible way but I'm honestly interested in how much impact such a product can have on the environment if handled responsibly.
    – Elmy
    Jul 9, 2022 at 15:14
  • Thanks @Elmy, I've added some links for you
    – Flirgle
    Jul 10, 2022 at 5:51
  • Thanks a lot for the links. I honestly didn't expect that. I was convinced that topical flea treatment was the most convienient option because of the ease of application, but this is certainly a downside to keep in mind.
    – Elmy
    Jul 10, 2022 at 8:53

1 Answer 1


This is a challenging question to answer, because the parasiticides we commonly use are used because they are highly effective. Parasiticides that are better for the environment are probably going to be less effective to treat the parasites.

One environmental concern with some of these topical medications is that they end up in drains or directly in water, perhaps from bathing or the dog going into a body of water too soon after topical application. See Little et al. (2020).

Parasites can be at the very least a big nuisance, and at worst life threatening. Animals die from complications of flea infestations all the time, and other parasites such as heartworm and lungworm are becoming increasingly prevalent. These are parasites that we can easily prevent.

I would suggest an oral parasiticide may be safer for the environment than a topical in some instances. There are a number of different products, but commonly used include isoxazolines such as afoxolaner (Nexgard), lotilaner (Credelio) and fluralaner (Bravecto). These are really only effective against fleas and ticks. One concern with these medications is that they undergo hepatic metabolism and there may still be low levels of drug excreted in faeces. The environmental impact of this could be mitigated by prompt clean up and safe disposal of any faeces. I could not find any studies assessing the environmental impact of these drugs due to faecal contamination, but I am sure it is not zero.

For internal parasites like lungworm, there are fewer options. In the UK the two main products to treat lungworms are imidacloprid/moxidectin (Advocate) and milbemycin oxime/praziquantel (Milbemax). Milbemax is an oral, so may be the one to go with.

That being said, one may be able to reduce the environmental impact of topical medications such as fipronil or imidocloprid if making sure to avoid any contact with water for several days after application.

There is not going to be any solution that has no environmental impact, but judicious and careful use of these drugs is possible.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.